Impact-type rippers include an eccentric cam which functions to intermittently apply an impacting force to a ripper tip for rock ripping purposes. The eccentric cam is aligned with the ripper tip to provide an in-line application of impacting forces thereto, via an intermediate ring-like impact member and impact receiving member. This type of impact ripper is fully disclosed in U.S. Pat. No. 3,868,145, issued on Feb. 25, 1975 to Delwin E. Cobb, Et Al., and assigned to the assignee of this application.
Although impact rippers of this type function quite well, the solid supporting shank for the ripper tip exhibits an impact spring rate that is approximately eight times stiffer than the hardest rock that can be ripped. This relatively high spring rate induces high peak impact forces in the ripper mechanism which could affect the desired service life thereof. In addition, impact energy is dissipated due to the mismatch of the mechanical impedance between the impact member and the shank and between the ripper tip and rock being worked.
Furthermore, conventional impact rippers are designed for relatively shallow cutting depths, e.g., 23 cm. Any attempt to offset the ripper tip from the eccentric cam and attendant impacting mechanisms requires a substantial lengthening of the shank, having the ripper tip secured thereon. The mass of the shank is increased to thus increase internal impacting forces without any appreciable increase in the ripping forces applied to rocks by the ripper tip. Such internal impacting forces tend to produce high moments which cause increased pivot pin loads and also induce ripper tip deflections, resulting in lower cutting efficiency.
The present invention is directed to overcoming one or more of the problems as set forth above.